The present invention relates to current sources and, more particularly, to a current source for providing an output current the magnitude of which is digitally controlled.
There are many uses for a current source for providing an output current the magnitude of which is controlled by an applied input signal thereto. For example, personal computers require keyboards for inputting ASCII (American Standard Code for Information Interchange) alpha-numeric information to the main computer unit. Most keyboards consist of several Light Emitting Diode status indicators and an audio tone generator for producing various audible status indications among other things.
There is need for a current source that can be interfaced with a microprocessor unit (MPU) in order to generate the status indications an output logarithmic current function, in response to receiving digital control signals from the MPU.